Liquid fuse



R. H. EARLE LIQUID FUSE Jan. 8, 1935.

Filed Nov. 14, 1932 2 Sheets-Sheet 2 7 6 H/ 4l* ma A Lvmnm 65H2. /g/J" E s Cttorneg Patented Jan. 8, 1935 UNITED1 STA-TiasA LIQUID FUSEA 1 y l vRalph H. Earle, Wauwatosa, Wis., assignor l Line Material Company, South Milwaukee, Wis.,4 a corporation of Delaware Application November 14, 1932, Serial No. 642,502

v 12`r claims.

"I'his invention relates to liquid fuses, and'is an improvement over that disclosed in the co-pending application Serial Number 609,453 filed May 5, 1932, for Liquid fuses jointly with' Walter E. Mittelstadt.

In liquid fuses it isthe customary practice to provide a tube of glass or other insulating material within which an arc extinguishing liquid is carried.y "An upper and a lower contact are provided connected by a fuse link and a ilexible cable, a spring being employedfto draw the lower portion of the fuse downwardly when the fuse blows.

These devices as heretofore made are subject to the defect in that an `arc is frequently established and plays about' and damages the upper contact, often cracking and breaking the glass.

This invention is designed to provide a liquid fuse which will prevent arcing at the upper contact, which greatly lengthensthe path ofthe arc and introduces a hairpin turn in the path'of the arc, which protects the glass or insulating tube and the upper contact, and which shoots the products of ycombustion far away from the fuse contacts, and in which means are provided, as by means of a rupturable diaphragm, for completely sealing the tube in vits normal condition, such diaphragm, however, in no way interfering 'with the above outlined results.

Ingreater detail further objects are to provide a liquid fuse having a main or stationary insulating tube of glass or other suitable material and a movable insulating tube which may be of fiber or of other insulating materialwhich is initially housed within the glass tube and is automatically moved upwardly when the fuse blows and projects from the glass tube and from the upper contacts, and which'thus substantially instantly elongates the path which an arc would haveto follow and at the same time forms a vent which projects the products of combustion far away from the fuse contacts.

'I'his invention is an improvement over that described in the above identied co-pending application, and has for its additional objects the pro'- vision of means for positively startingv or forcing the fiber or otherinsulating tube outwardly from the main tube, such tube subsequently being drawn or forced farther outwardly by the gas pressure produced by the arc boiling the liquid, so that there is noy possible chance of failure of the device under any condition of fuse rup-turing load.

The device is so made that the load for which the device will operate may be suddenlyapplied or ymay be gradually applied, but in all'cases the positiveoperation oi the apparatus is assured.

Embodiments of the invention are shown in the accompanying drawings, in which:-

1 Figure 1 is," an elevation-of a liquidfuse, with parts broken away and parts in section.

n gurer2 is a rtop View of Figure 1, veryA much enlarged and with parts broken away.

Figure"3`is 'a vie'w' showing a modied form oi' the invention. v,

i Figure 4 is aview showing* a modified form Aof the invention in' 'which a cap `or stopper is employed for" initially starting 'the tube.

i Figure 5l is a view showing a further form of the invention, in which means are provided for retracting the 'slidable tube 'after it has been ejected; j

Figure 6is 'a sectionalview on the line 6-6 of Figure 5. *ff f Y' "rr-Referring tothe drawings, vparticularly Figures 1 and 2,; it will be seen that the liquidy fuse comprises kamain tube 1 which may be of glass lor other similar materialand 'is adapted to contain an arc extinguishingliquid in the usual manner. 'Ihis tube is provided with an upper contact 2 and a lower contactI 3. Within'thetube a fuse link 4is provided adjacent its upper end and is carried byr al supporting spring bridge5, as indicated in-Figures1and2. n

It is preferable toform this fuse link so that there are two ribbons -indicated at 6 at its upper end which are looped around the curved feet of lthe 'springfbridge 5, vas shown in Figure 1, and are clamped between such'curvedfeet and the 'bottom' of notches or 'slots' A'l within which the ends of this togglelike spring bridge 5 are-seated. If desired; ajcork 8 may cover the reduced portion Thelower end of the fuse link is connected with the lower contact i3 by means of `a flexible cable 9 ,`acoiledspring'10 being also attached to the y'lower end of the fuse link for drawingA the lower portion of the fuse link downwardly after the fuse has' blown.- 1

The'upper' contact 2 Acomprises a clamping ring phragm :12 formed of thin, relatively soft, metal or alloy so as to seal the device and prevent evaporation or loss of the arc-extinguishing liquid.

or nut 11 whichis screw threaded to the upper end i of the upper contact'and Aclamps a rupturable dia- A'stop ring 13 is clamped beneath the dia- V` phragm 1'2' by the nutll and is provided with a central opening '14),'v see Figure 2, through which the fuse parts may pass. It is also provided with tube 1 and extends downwardly around the fuse link and a considerable distance below the fuse link. It is provided with a reduced upper portion 16 and a shoulder 17 is formed between the reduced upper portion and the lower portion.y This' shoulder is adapted to engage the stop ring 13 and to thereby arrest the outward motionof the slidable insulating tube 16.

The tube 16 is urged outwardly by means of a compression spring 19 which is of. larger diameter than the spring 1?(1. The spring. 19 is than the spring 10. y f

Under normal conditions when the fuse is intact, the parts are in the positions shown in Figure 1. When the fuse blows, the diaphragm 12 is ruptured and. blown outwardly and the pressure of the bridge 5 'or suspension member for the fuse link against the upper end of the slidable tube 16 is removed.

The spring 19 operates to project the tube 16 outwardlyV in. a positive mechanical manner.. The gas pressure generated by the are boiling the liquid produces a pressure upon the lower edge of the tube which is not balanced by the atmospheric pressure on the upper edge ofthe tube and this pressure, together with the frictional drag. produced by the outwardly rushing gases, force the tube outwardly and complete its outward motion until the shoulder 17 strikes against the 'stop ring 13. The bridge piece 5 and suon remaining portions of the upper end of the fuse link are blown outwardly and are freely -detached from the slidable tube. f f

Suppose that a very small load although. sudicient to rupture the lfuse is gradually applied. Obviously there would not be as violent an evolution of gasesI as ifV a dead short-circuithad occurred. Nevertheless, this device Ywill function equally well under these conditions for the initial movement of theslidable tube is mechanically imparted thereto and is not dependentv uponthe outwardly rushing gases. After the tube has been started outwardly, the gas pressure and the outwardly rushing' gases complete the outward motion of the slidable tube.

, In the form of the invention shownin Figure 3 the ber tube 20 is substantiallysimilar to the ber tube 16 previously described, except that it is provided witha bead or flange 21 about its upper4 end beneath which the feetv of -the bridge member 5 hookuwhen the parts are in their normal position.

The rupturable diaphragm 12 is heldin place by the clamping nut 11, as previously described, but it is preferable to provide a split stop ring or two-part stop ring 22 in the .form shown in Figure This stop ring is itself provided with notches or slots 23 within whichthe feet of the bridge member 5 seat. It is provided with an inwardly projecting flange 24 which is adapted to engage the shoulder 25 formed on the fiber tube to arrest its outward motion at the extreme upper limit of its outward stroke.

y This invention also provides means whereby a mechanical pull is imparted t the slidable tube. To initiate its motion when the fuse blows, this mechanical pull or outward pushing movement is imparted to the tube due to the fact that the bridge member 5 hooks beneath the upper ange 21 of the slidable tube and as the upper part of the fuse, the bridge member and the cork 8 are blown outwardly, it is obvious that this bridge member suddenly draws ythe tube outwardly and thereby mechanically initiates its outward motion. The outward motion of the slidable tube is completed as previously described. AIn. the form of the invention shown in Figurel 4, the slidable fiber tube 26 is free from any shoulder or flange at its upper end. It is, however, providedfwith ashoulder 27 corresponding to the shoulders 17 and 25 previously described.

`Fhis vform. of the invention has been illustrated as providing a tapered shoulder 27 and a correspondingly tapered portion 28 formed on the stop ring 29,A although this form or the flat shoulder may be yused onanyoffthe several forms of the invention., `|llhe tapered shoulder, however, acts somewhat' as a cushion and arrests the motion of the tube in a more gradual manner than the abrupt shoulder previously described. There seems to be a slight cushioning action inthe actual operation of the device. However, in this form of theifinvention the stop ring 29`is screwed into' the upper contact vBtlcar'ried at the upper end of the main tube 1.

A closure cap 31fis provided vand is equipped with a tapered stopper-like portion 32 which nts into the tapered upper end of the tube 26, as shown, and thus holds the tube 26 in place,

and in addition closes the openupperend of the upper contact 30.

-It is to be noted from Figure 4 that thefuse link 33 is attached to the stopper or central portion 32 of the cap.. The lower end of the f use link is drawn downwardly by the spring 10l and consequently the cap 31 is held tightly in place. It is preferable to provide a knife redge 34 at the upper end of the contact 30, as shown in Fgure 4,so that this knife edge bears against or seats against theunderside of the cap 31. MA tight seal is thus secured due to the fact that the cap isV drawn downwardly by thespring 10 and consequently the knife edge insures a secure airtight and liquid-tightV seal or joint between thev upper contact 30 and the `cap 31.

.When the fuse blows, the cap 31 is released and is blown upwardly away from thedevice.

This `cap draws the ber tube 26 along lwith it until the Ashoulder 27. engages the shouldered portion 28. The cap 311 isthen blown from the` 4and also vas av means for sealing the main fuse 4tube at the upper end of the upper contact. Itis also preferable in this form of the invention to provide the cap 31 with an annular, downwardly projecting ilange 35 which ts over the adjacent upwardly projecting portion of the upper contact 30. l

In' the form of the invention shown in Figure .5 a relatively shorter insulating tube or sliding tube 36 is provided. This sliding tube is provided with a stop shoulder 37 which maybe tapered and which engages thejtaperedshoulder `38 formed on the lower side of the stopy ring A d' k 46 isattached to the upper end of the spring 10 in any `suitable manner. For example, the fitting 47 may passv through the disk 46, and due tothe fact'tha't' an attaching screw 48 joinssuch fitting to thev lower end of the link, itis apparent that the fitting 4'7 or connector vcannot be drawndownwardly through the disk. However, the `-disk 46normally stands in about the position-,shown in Figure 5 intermediaytegthe yends of the slidable tube 36. It is preferable to form the disk 46 with a plurality 'of `o'penings'49 or it maybe formed in any other mannerl to provide a spider-like structure or openy structure sov that the arck extinguishing liquid willnot'act to prevent the free sliding motion `of the disk in a manner hereinafter to appear.

When the iuse blows, the bridge member 41 and whatever remainsof the -upper portion of the fuse link, with the cork 8 are blown outwardlythrough the then'ruptured diaphragm Y43; Inasmuch as the endsvof the'bridge member or `suspension member 41 are-hooked into the groove 44 in the slidable tube, litis apparent that this slidable tube is suddenly mechanically started outwardly and its outward motion is thereafter completed in the manner previously described. This action is very fast, indeed, and outruns the action of the -spring 10.V IHowever, an instant later the spring'lt) contracts and the stop or disk 46 is drawn=downwardly into engagement with the lower shoulderf45. The slidable tube is thus drawn downwardlyback into the device by means of the spring I andy itv will 'keep on downwardly to' the lowerl end of the glass tube 1, sinking within thev arc extinguishing liquid.

The tube 36 or in fact any of the slidable tubesdisclosed'may be formed of any suitable insulating material, preferably of iiber. They may, however, be formed of other material, such, for instance, as glass, if desired, to prevent obscuring the vision of an inspector when examiningthe device. If they are formed of glass, it is obvious that the stopl rings would then bev formed of somewhat yielding material, such as fiber,l bakeli'te, or other suitable material. In-addition to this, it is Within the scope of this invention to form thelower portion of vany of' the slidable insulating tubes of glass and the upper portion of yother material. Also'if it is desired, the lower end of thetube shown in Figure-5 may be weighted, although ythis has not been found necessary in the actual tests of the device. v y Y f Y vIn the rform of the invention shown in Figure `5, the slidable'tube slides downwardly completely away from the upper Contact. However, in all forms of the invention the sliding tube is rst mechanically started outwardlyby mechanical means so thatit-has a positive initial outward motion. Thereafter the fuse suspension means infwhatever formvit may'take is disengaged from the slidable tube and rthe'subsequent completion of the outward motion ofthe slidable tube is accomplished b'y the outwardly rushing gases.

In'actual tests of this invention it has been found that apositive assured 'action of the fuse occurs under all? conditions. The fuse always clears and the slidable tube is always positively pulled outwardly by mechanical means at the initiationv of its routward motion. Also the out- Wardly travelling tube directs the gases or vapors and the discharged liquid -far away from the upper contact.

The slidable tube being projected outwardly at the time of the' blowing of the fuse forms a hairpin turn in the arc as the tube moves outwardly, and forces the arc to pass through the bore of the tube' and' thereafter over to the upper contact even at the early portion of lts outward motion. Thus the path of the arc is greatly lengthened and the arc is quickly snapped out and a very sharp bend is formed therein.y

It is impossible for `'an arc to strike from the spring lug to the inner portionof the contact 30, because the portion of the tube lying below theshoulder 27 covers the contact 30 at the time the shoulder 27 has Vcontacted with the shoulder 28; The' same action occurs in all forms of the'invention.-v

It will be seen further that all forms of the device maybe simply constructed and are relatively' inexpensiver to manufacture.

A'Although this invention has been described in considerable detail, it is to be understood that such description is intended as illustrative rather than limiting, as the'invention may be variously embodied and is to be interpreted as claimed. rvI claim:

1. A liquid fuse comprising an insulating tube adapted to contain an arc extinguishing liquid and having upper andflower contacts, said upper contact having an open central portion, a rupturable diaphragm closingthe opening through said upperfcontalct, a 'fuse link electrically connected to -s`aid`contacts', a sliding tube located within said main tube adapted to be projected outwardly upon rupturingvof said fuse link, and meansdetachably interlocking with said sliding tube for mechanically initiating the outward motion of saidv sliding tube when said fuse blows.

2. A liquid fuse comprising an insulating tube adapted to contain an arc extinguishing liquid and having upper and lower contacts, said upper contact having an open central portion, a rupturable diaphragm closing the opening through said upper contacta fuse link electrically connected to' said contacts, a sliding tube located within said main tube adapted to be projected outwardlyvuponruptur'ing of said fuse link, and means for mechanically initiating the outward motion of said sliding tube when said fuse blows, said means temporarily holding said sliding tube in place.

3. A liquid fuse comprising an insulating tube adapted to contain an arc extinguishing liquid and having upper and lower contacts, said upper cont-act having an open central portion, a rupturable diaphragm closing Vthe opening through said upper contact, a fuse link electrically connected to said contacts, a sliding tube located within said main' tube adapted to be projected outwardly upon'rupturing of said fuse link, and means for mechanically initiating the outward `motion of said sliding tube when said fuse blows,

said means controlled'by'said fuse link and tenir;V

porarily holding said sliding tubev in place.

4. A liquid fuse comprising an insulating tube adapted to containan arc extinguishing liquid and having upper and lower contacts, a fuse link electrically connecting said contacts, suspension means for said fuse link adjacent said upper contact, a tension spring drawingdownwardly upon said fuse link, and a slidable tube located within said main tube normally extending from adjacent the upper end of said insulatingtube to a point a material distance below the lower edge of said upper contact and extendingovera portion of said tension spring and adapted to be projected outwardly when said fuselink blows, said suspension means being blown outwardly when said fuse blows, said suspension means and said slidable tube being mechanically connected, whereby when said fuse blows said suspension means initiates the outward motion of said slidable tube, the generated gases completing the outward travel of said slidable tube.

5. A liquid fuse comprising an insulating main tube adapted to contain an arc extingushing liquid and having upper and lower contacts, the upper contact having an open central portion, a rupturable diaphragm normally closing the open central portion of said upper contact, a fuse link electrically connecting said contacts and located within said tube, a tension spring located within said'tube and attached to the lower portion of said fuse link, a suspension member forsaid fuse link supported from said upper contact, and a slidable tube surrounding said; fuse link and adapted to be projected outwardly through said upper contact when said fuse link blows, said slidable tube being connected to said suspension means and being located below said diaphragm, said slidable tube having a shoulder thereon and said main tube having means for engaging said shoulder to prevent complete expulsionof said slidable tube when said fuse blows.`

6. A liquid fuse comprising an insulating tub adapted to contain an arc'extinguishing liquid and having upper and lower contacts, the upper contact having an open central portion, va rupturable diaphragm normally closing the open central portion of said upper contact, a fuse link electrically connecting said contacts and located within said tube, a tension spring located within said tube vand attached to the lower portion of said fuse link, a suspension member for said fuse link supported from said upper contact, and a slidable tube surrounding said fuse link and adapted to be projected outwardly through said upper contact when said fuse link blows, said slidable tube being connected to said suspension means and being located below said diaphragm and below said suspension means.

7. A liquid fuse comprising a main tube of insulating material adapted to contain an arc extinguishing liquid and having upper and lower contacts, a fuse link electrically connecting said contacts, a tension spring drawing downwardlyupon said fuse link, a slidableV tube surrounding said fuse link and adapted to project outwardly from said main tube, said slidable tube extending downwardly from adjacent the upper end of said main tube to a point a material distance below said upper contact and surrounding a portionv of said spring, and a suspension member for said fuse link supported from said upper contact, said suspension member and said slidable tubev having interengaging portions,

8. A liquid fuse comprising a main tube of insulating material adapted to; contain an arc extinguishing liquid and having upper and lower cone tacts, a; v.fuse link electrically.. connecting said contacts-,-.a slidable tube surrounding said fuse link andY adapted to project outwardly from said main tube, ,a suspension member for said fuso link supported `from saidupper contact, said suspension member and said slidable tube having detachable, interlocking portions, and means for arresting the` outward motion oi said slidable tube at a predetermined point, said means being carried jointly by said main tube and said slidable tube.

9. A liquid fuse comprising a main tube of insulating material adapted to contain an arc extinguishing liquid andhaving upper and lower contacts, a `fuse link electrically connecting said contacts, a slidable tube surrounding said fuse link and adapted to project outwardly from said main tube, a suspension member for said fuse link supported from said upper contact, said suspensionmember and said slidablevtube having interengaging portions, and means carried di rectly by said main tube and said slidable tube for arresting the outward motion of said slidable tube at a predetermined point, said interengagable portions of said slidable tube and said sus pension member being detachable when said slidable tube is at its outermost position, whereby said suspension member may be blown from said slidable tube at the limit of motion of said slid able tube. y

l0. A liquid fuse Lcomprising a main tube of insulating material adapted to contain an arc extinguishing liquid and having a lower contact and an annular' upper contact, a rupturable diaphragm normally closing said upper contact, a suspension member supported from said upper contact, a fuse link extending downwardly from said suspensionr member andV electrically connected to said contacts, a spring drawing downwardly upon the lower end `of said fuse link, said suspension member being in the form of a toggle with inwardly turned ends, and a slidable tube surrounding .said fuse link and interlocked with the inturned ends of said suspension member, whereby when saidV fuse link blows said diaphragml is blown outwardly and said suspension member is blown outwardly through said annular upper contact, thereby drawing said slidable tube outwardly.

11. A liquid fuse comprising a main tube of insulating materialy adapted vto contain an arc extinguishing liquid and having a lower contact and an annular upper contact, a rupturable diaphragm normally closing said upper contact, a suspension member supported from said upper contact, a fuse Vlink extending downwardly from said suspension member and electrically connected to said contacts, a spring drawing downwardly upon the lower end of said fuse link, said suspension member being in the form of a toggle with inwardly turned ends, a cork surrounding'y said fuse link and located below said suspension member, and a slidabletube surrounding said fuse link and interlocked with the inturned ends of said suspension member, whereby when said fuse link blows said diaphragm is blown outwardlyand said suspension member is blown outwardly through said annular upper contact,

thereby drawing saidslidable tube outwardly.

12. A liquid` fuse comprising a main tube of insulating material adapted to lcontain an arc extinguishing liquid and having a lower contact andan annularl upper contact, a slidable tube adapted to' slide outwardly through said upper link, and means for establishing an operative contact when said fuse blows, a suspension memconnection between said spring and said slidable ber supported from said upper contact and entube after said slidable tube has been projected gaging said slidable tube, a fuse link carried by outwardly, whereby said slidable tube is subse- 5 said suspension member and projecting downquently retracted and drawn downwardly into 5 wardly therefrom, a tension spring for drawing said main tube. downwardly upon the lower end o1' said fuse RALPH H. EARLE. 

